Biomedical subjects

A B Thomson

Publications and source records attributed to A B Thomson.

At least 235 records · Page 13Linked to original sources

PubMed1986

Vitamin C status in 137 outpatients with Crohn's disease. Effect of diet counseling.

Vitamin C intake, and serum and leukocyte ascorbate levels were assessed serially over 6 months in 137 outpatients with Crohn's disease. Vitamin C intake was low in 18% of males and 37% of females. Serum ascorbate levels were suboptimal in 11% of males and 18% of females. Leukocyte ascorbate levels were low in 26% of males and 49% of females. Serum ascorbate levels were more frequently below the reference range in patients who smoked, but neither the serum nor the leukocyte ascorbate levels were affected by Crohn's disease activity, the use of an oral contraceptive agent, or by taking prednisone or sulfasalazine. Monthly diet counseling sessions significantly increased vitamin C intake, led to more patients consuming a normal ascorbate intake, and to a normalization of serum ascorbate values. We did not establish the importance of these ascorbate abnormalities on the clinical course of Crohn's disease. We conclude that low serum or leukocyte ascorbate levels are relatively common in patients with active or inactive Crohn's disease; these abnormalities are due in part to the reduced intake of dietary ascorbate; and the ascorbate status in patients with Crohn's disease may be normalized by improving the dietary intake of vitamin C.

Adult↗

PubMed1986

Pericarditis and ulcerative colitis.

We report an 18-year-old man with a pericardial effusion complicating idiopathic ulcerative colitis. Circulating immune complexes were absent. He responded to sulfasalazine and prednisone, with resolution of the pericarditis and improvement in the symptoms of his inflammatory bowel disease (IBD). We recommend looking for pericardial effusion or pericarditis in patients with IBD and chest symptoms, and for IBD in obscure cases of these cardiac disorders.

Adolescent↗

PubMed1986

Resection of rabbit ileum: effect on jejunal structure and carrier-mediated and passive uptake.

Adaptive changes occur in nutrient uptake following intestinal resection. A previously validated in vitro technique was used to measure the rate of uptake of solutes six weeks following surgical removal of the distal half of the small intestine in the rabbit. The rate of jejunal uptake of a homologous series of fatty alcohols, cholesterol, and six bile acids was unchanged in the resected animals. The uptake of short- and long-chain length fatty acids was also unchanged following resection, although there was a modest but significant increase in the uptake of decanoic and dodecanoic acid. The incremental change in free energy, integral of delta Fw----l, was increased in the jejunum of resected animals when assessed with the medium chain-length fatty acids, but was unchanged when estimated from the uptake of long chain-length fatty acids. The value of delta integral of Fw----l for bile acids was similar in the jejunum of control and resected animals. There was an increase in the maximal transport rate (Jdm) for D-glucose, galactose and L-leucine, an increase in the Michaelis constant (Km) for 3-O-methylglucose, and an increase in both the Jdm and Km for fructose. There was no change in the passive component of the uptake of these solutes following intestinal resection. In the resected animals there was no significant increase in the height, width, and surface area of the jejunal villi, the number of mucosal cells per villus, or in the mucosal surface area, although there was a significant increase in the weight of the scraped mucosa and in the height of the microvilli. The modifications in the active and passive kinetic constants were not related to the alterations in the microvillus surface area, and changes in the Km or delta integral of Fw----l were not due to any variation between control and resected animals in the effective resistance of the intestinal unstirred water layer. These results indicate that, ileal resection was not associated with changes in the effective resistance of the intestinal unstirred water layer; the variable changes in the uptake of passively adsorbed solutes following resection suggests a functional heterogeneity of the villus towards passive permeation; estimation of the incremental change in free energy of the intestine using a homologous series of saturated fatty acids may provide variable results depending upon the chain length of the probes.(ABSTRACT TRUNCATED AT 400 WORDS)

3-O-Methylglucose↗

PubMed1986

The development of the small intestine.

The remarkable degree of coordination between the development of various aspects of gastrointestinal function suggests that the process may be triggered by a single or a few central mechanisms, such as weaning and (or) hormones. Precocious development of enzyme and transport function can be induced by exogenous thyroxine and corticosteroids, while thyroidectomy and adrenalectomy abolish the normal pattern of postnatal development. These hormones may have a primary or a permissive role. Activation of the dormant hormonal mechanism could be controlled by a genetically coded biologic clock, such as chronologic age, or by a biological signal such as body size and oral intake. Generally speaking, shortly after birth, there are increases in the intestinal mucosal surface area, brush border membrane enzymes, and carrier-mediated transport. These adaptive changes occur as a result of the genetic endowment of the animal, but may be modified by environmental factors, particularly nutrient intake.

Aging↗

PubMed1986

The aging gut.

A spectrum of changes occurs in the function of the gastrointestinal tract throughout the life of the animal. With aging, there is a decline towards newborn levels of the villus surface area and brush border membrane markers, but the absorption of some nutrients continues to increase (such as glucose and vitamin), whereas the absorption of some nutrients falls (such as cholesterol) and fatty acids). Clearly there is a distinction between age-related alterations in intestinal form and function, and some of the enzyme- or carrier-mediated changes are substrate specific. With aging, the structure and brush border membrane composition of the intestine tends to regress towards newborn levels. It remains to be clarified whether these changes are a benefit to the animal, whether they represent a degeneration of normal function, and whether these changes are the cause or the effect of various age-related alterations in metabolic and physiological function.

Aging↗

PubMed1986

Endothelium-dependent relaxation and experimental atherosclerosis in the rabbit aorta.

This study was undertaken to determine whether the production or release of the endothelium-dependent relaxatory factor is impaired in atherosclerotic New Zealand White rabbits. Atherosclerosis was induced by feeding a diet containing 2% cholesterol for 6 weeks. The production or release of endothelium-dependent relaxatory factor was assayed as follows. A 5-cm length of aorta donor was perfused with Krebs-bicarbonate buffer and the perfusate drained over a deendothelialized ring of recipient aorta set up for recording isometric tension. The recipient was precontracted with norepinephrine (0.2 mumol/L) in the perfusate. When acetylcholine was added to the perfusate, the recipient relaxed in a dose-dependent manner. This assay was used to compare the relaxatory responses produced in recipient rings by adding acetylcholine to donors from atherosclerotic and control rabbits. The relaxation produced by atherosclerotic donors were smaller than those generated by control donors (16.5 +/- 4.9 vs. 32.7 +/- 5.3%; n = 10, p less than 0.05). It is suggested that in atherosclerotic rabbits the ability of aortic endothelium to produce or release endothelium-dependent relaxatory factor is impaired.

Acetylcholine↗

PubMed1986

Effects of sulfur dioxide on pore populations of canine tracheal epithelium.

The bioelectric and barrier properties of the tracheal epithelium in nose-breathing dogs and in dogs that had been exposed for 75 min to compressed air or to two high concentrations of SO2 were measured and compared. We also studied tissues that had been treated with chloroform. Based on a model of restrictive diffusion we demonstrated heteropores (6 and 250 A) in the control tissues. Bioelectric changes due to 100-ppm SO2 were minimal. After exposure to 500 ppm SO2, adverse changes in the bioelectric properties were focal; they were marked in 8 out of 12 animals but were less striking in the other 4. Nonelectrolyte permeability increased with an increase in SO2 concentrations. Small pores were still present in the tissues severely affected by SO2 but they were absent in chloroform-treated tissues. Scanning electron microscopy of tissues from animals exposed to 500 ppm SO2 showed that in the same dog tissue appearance varied from normal to one of repair (normal bioelectric properties) or one of marked exfoliation of ciliated cells (abnormal bioelectric measurements).

Animals↗

PubMed1986

Recurrent Clostridium difficile-associated colitis responding to cholestyramine.

We describe a patient with relapses of Clostridium difficile cytotoxin-positive pseudomembranous colitis (PMC) after treatment with vancomycin, a course of metronidazole and a trial of bacitracin. She remains free of disease after a prolonged course of cholestyramine. We suggest there may be a role for anion-exchange resins in patients with PMC relapsing after vancomycin therapy.

Adult↗

PubMed1986

Dietary fat content influences uptake of hexoses and lipids into rabbit jejunum following ileal resection.

After 6 weeks' feeding on a high-fat or low-fat diet, the in vitro uptake of hexoses and lipids was measured in control rabbits with an intact intestinal tract, and in animals submitted to the surgical removal of the distal half of their small intestine. Jejunal villus height, villus surface area and mucosal surface area were higher in unresected control rabbits fed the low- as compared with the high-fat diet, whereas dietary fat content had no effect on villus morphology in resected animals. Mucosal surface area was similar in control and in resected animals fed the high-fat diet, but was lower in resected than in control animals fed the low-fat diet. The active and passive transport properties of the jejunum were influenced by dietary fat manipulation. These absorption changes were qualitatively and/or quantitatively different in animals with an ileal resection from those in animals with an intact small intestine. Dietary fat manipulation had a different effect on the uptake of each lipid probe. The effective resistance of the intestinal unstirred water layer also adapted to changes in the dietary content of fat, but the changes in uptake of hexoses, fatty acids and cholesterol cannot be simply explained by alterations in this diffusion barrier, or by changes in the villus morphology. These findings indicate the importance of dietary fat on villus structure and transport function and their adaptation to ileal resection.

Adaptation, Physiological↗

PubMed1986

Adaptation of colonic uptake of hexoses and lipids following ileal resection: effect of variations in the fat content of the diet.

This study was undertaken to determine the effect of varying the dietary composition of fat (corn oil and lard) on the colonic uptake of lipids (medium-chain-length fatty acids, cholesterol and decanol) and hexoses (D-glucose, galactose and 3-O-methyl glucose) in control rabbits with an intact intestinal tract, and in animals submitted 6 weeks previously to the surgical removal of the distal half of their small intestine. Food intake was similar in the control and resected animals fed the high-fat (HF) or the low-fat (LF) diet. Body weight gain was lower in control animals fed LF than HF, but was lower in resected animals fed HF than LF. Colonic adherent mucosal fluid volume was unaffected by diet or by ileal resection, but colonic weight was lower in resected than control animals fed LF. Colonic uptake of glucose and 3-O-methyl glucose but not galactose was changed by ileal resection and by dietary fat changes. Colonic uptake of fatty acids and cholesterol was also different in HF than LF, and in resected as compared with control animals, but these changes were not explained by variations in the effective resistance of the colonic unstirred water layer. Thus colonic transport function is altered by the manipulation of the dietary content of fat and by resection of the ileum.

Adaptation, Physiological↗

PubMed1986

Effect of Ensure, a defined formula diet, in patients with Crohn's disease.

A prospective controlled 6-month study was undertaken to compare the effect of Ensure, a defined formula dietary supplement, and diet counselling in 122 outpatients with Crohn's disease. The compliance to Ensure was poor due to a high incidence of side effects. Taking any amount of Ensure reduced the need for surgery and the amount of hospitalization. There was a trend for patients receiving Ensure to experience a decline in the value of their Crohn's disease activity index (p less than 0.10). No consistent effects of Ensure were seen on the amount of work missed due to Crohn's disease, in laboratory measurements, in the need for prednisone or Salazopyrin. The vitamin B12 intake was improved, but otherwise nutrient intake declined due to a decreased food intake. Thus, certain beneficial clinical trends were associated with taking Ensure, but larger numbers of compliant patients will need to be studied to better assess the long-term role of defined formula diets in the management of outpatients with Crohn's disease.

Adult↗

PubMed1986

Dietary fat selectively alters transport properties of rat jejunum.

The influence of dietary fatty acid composition on intestinal active and passive transport function, brush border membrane composition, and morphology was examined in rats. Animals fed a semisynthetic diet high in saturated fatty acids demonstrated enhanced in vitro jejunal uptake of decanoic, dodecanoic, palmitic, stearic, and linoleic acid, as well as cholesterol and chenodeoxycholic and taurochenodeoxycholic acid, as compared with uptake in animals fed a semisynthetic diet high in polyunsaturated fatty acids but equivalent in total content of fat and other nutrients, or as compared with Purina chow. Feeding the saturated fatty acid diet was also associated with reduced jejunal uptake of a range of concentrations of glucose, enhanced ileal uptake of leucine, unchanged uptake of galactose, and lower uptake of decanol. The semisynthetic diets did not alter brush border membrane protein, sucrase or alkaline phosphatase activities, cholesterol, or total phospholipids, although the percentage of jejunal amine phospholipids was higher than in rats fed chow. The morphologic differences between the jejunum and ileum were abolished in animals fed the high polyunsaturated fatty acid diet; in rats fed the high saturated fatty acid diet, there was reduced mean ileal villus height, width, thickness, surface area, cell size, and villus density, as well as reduced mucosal surface area. The changes in jejunal transport were not correlated with the alterations in morphology, unstirred layer resistance, food intake, or body weight gain. It is proposed that small changes in the percentage of total dietary lipids composed of essential and nonessential fatty acids (without concurrent alterations in dietary total fat, carbohydrate, or protein) influence active and passive intestinal transport processes in the rat.

Animals↗

PubMed1986

Late effects of abdominal radiation on intestinal uptake of nutrients.

The late effects of variable doses of abdominal irradiation on in vitro jejunal uptake were examined. The uptake of glucose, galactose, cholic acid, medium-chain length fatty acids, and decanol was studied 6 and 33 weeks following 300, 600, or 900 cGy abdominal irradiation. The intestinal morphological characteristics were similar 6 and 33 weeks after radiation. The uptake of cholic acid was unaffected by abdominal irradiation, but for glucose, galactose, and four fatty acids the direction and magnitude of the changes in uptake were influenced by the dose of irradiation and by the interval following exposure. The greater uptake of decanol at 6 weeks but lower uptake of decanol at 33 weeks reflected changes in the resistance of the intestinal unstirred water layer. These absorption changes suggest that the intestine may not be capable of correcting the transport abnormalities arising from sublethal doses of abdominal irradiation.

Abdomen↗

PubMed1986

Effect of external abdominal irradiation on intestinal morphology and brush border membrane enzyme and lipid composition.

Previous studies have shown that external abdominal irradiation is associated with alterations in intestinal morphology and function. The activity of the jejunal brush border membrane (BBM) enzyme markers sucrase (S) and alkaline phosphate (AP) were not altered by 600 rad irradiation in the rat. In contrast, ileal BBM, AP, and AP/S were increased 3, 7/8, and 28 days postirradiation. The total lipid composition of the jejunal BBM was lower than in control animals only at 3 days postirradiation; this was due to a decrease in the total free fatty acid content. In addition to a lower total free fatty acid content, the ileal BBM contained an increased amount of total phospholipid (PL) which resulted in an increased phospholipid/cholesterol ratio at 3 days following irradiation. Variations in the BBM phospholipid composition occurred in both jejunum and ileum. In the jejunal BBM, the phospholipid composition changes did not alter the choline or amine phospholipid content; therefore, the choline/amine phospholipid ratio was unaffected by irradiation at 600 rad. In the ileal BBM, the phosphatidyl ethanolamine was increased at 3, 7/8, 14, and 28 days following irradiation. The choline/amine phospholipid ratio was not altered in the ileal BBM due to concomitant increases in lecithin content. Jejunal villus height, villus surface area, and the number of cells per villus were decreased at 3 days postirradiation, but increased by day 7/8 and 14 postirradiation to levels much higher than observed in control jejunal villi. The mucosal surface area was decreased at 3 and 7/8 days following irradiation but returned to control values by Day 14. Jejunal microvillus morphology was unaffected by irradiation. Few significant changes were observed in ileal villus morphology following irradiation at 600 rad. Ileal villus height, villus surface area, and mucosal surface area did not change, but the number of cells per villus initially decreased at 3 days and then increased beyond control values at 7/8 and 14 days postirradiation. Ileal microvillus height was significantly decreased only at 7 days postirradiation, while the number of microvilli per micron was increased only at 3 days postirradiation. This study suggests that changes in intestinal morphology and brush border composition may contribute to the altered passive permeation toward lipids which has been reported following abdominal radiation.

Abdomen↗

PubMed1986

Early nutrition and intestinal transport function: effect of low-cholesterol diet.

Intestinal structure and function change with aging and with manipulation of the diet. The present study was undertaken to assess the absorption of selected nutrients and the morphologic characteristics of the intestine of weaning rabbits fed chow for 2, 4, or 6 weeks, and to determine the effect of feeding a low-cholesterol diet (LCD) for 2 weeks on these changes. Over the 6-week period in the chow-fed rabbits, an increase was seen in the jejunal villus height, villus surface area, and mucosal surface area, whereas in the ileum no change occurred in the villus height, and a decrease in the mucosal surface area was seen. Feeding LCD for 2 weeks had no effect on the jejunal or ileal mucosal surface area, and returning to chow for 2 weeks after 2 weeks of the low-cholesterol diet (LCD-C) also had no effect on mucosal surface area. Food consumption was lower in animals fed LCD than in animals fed chow, but body weight gain was unchanged. With an in vitro technique, the jejunal, ileal, and colonic uptake of lipids was shown to change over 6 weeks in animals fed chow, with a decline in the value of the incremental change in free energy (integral of delta Fw----I) associated with the uptake of medium-chain fatty acids, and an increase in the uptake of dodecanol, suggesting lower effective resistance of the intestinal unstirred water layer. The jejunal and ileal uptake of glucose and leucine fell from 2 to 6 weeks of age. Feeding LCD for 2 weeks was associated with marked changes in transport: in the jejunum there was increased uptake of fatty acids (FA) 6:0, 8:0, 12:0, 14:0, and 16:0, dodecanol, glucose, and galactose, and reduced uptake of FA 10:0 and 18:0, cholic acid, and leucine. Feeding LCD abolished the site-related differences in integral of delta FW----I, and reduced the early age-related fall in integral of delta FW----I in the ileum and colon. With LCD-C some of the changes in uptake were returned to normal, whereas for others new abnormalities became apparent. Thus, (1) the intestinal structure and transport function of young growing rabbits undergoes complex alterations, with the direction and magnitude of the absorption changes depending on the probe and the intestinal site; (2) feeding LCD for 2 weeks alters the age-related process of intestinal development.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗

PubMed1985

Misoprostol, a synthetic PGE1 analog, in the treatment of duodenal ulcers. A multicenter double-blind study.

Misoprostol, a synthetic analog of prostaglandin E1, inhibits gastric acid production and is cytoprotective at doses well tolerated by patients in preliminary trials. This multicenter double-blind study was performed in out-patients with endoscopically demonstrated duodenal ulcers, to compare the efficacy in ulcer healing and the safety of two dosages of misoprostol and placebo. Up to six antacid tablets daily were permitted for pain. 308 patients enrolled and were randomized to three treatment groups: placebo, misoprostol 50 micrograms and misoprostol 200 micrograms. After two weeks of treatment, the three groups had similar percentages of patients with complete ulcer healing. However, after four weeks, 76.6% of patients taking misoprostol 200 micrograms q.i.d. had complete healing, compared with 42.6% on misoprostol 50 micrograms q.i.d. and 51% on placebo (P less than 0.001, 200 micrograms versus placebo). Patients taking misoprostol 200 micrograms used less antacid than the others. Diarrhea, mild and self-limiting, was present in 13% of the 200 micrograms group versus 5% on placebo. We conclude that misoprostol 200 micrograms q.i.d. is effective, safe and well tolerated in the treatment of duodenal ulcers.

Adolescent↗

PubMed1985

Comparison of cimetidine and ranitidine on 24-hour intragastric acidity and serum gastrin profile in patients with esophagitis.

Twenty-four-hour intragastric pH and serum gastrin profiles were monitored in six male asymptomatic patients who previously were found to have esophagitis on endoscopy and biopsy. They received cimetidine 300 mg qid (C), ranitidine 150 mg bid (R), or placebo (P) for one week each, utilizing the Latin-square design. The mean BAO was 0.4 +/- 0.2 mmol/hr, and the pentagastrin-stimulated MAO was 21.2 +/- 3.2 mmol/hr. In the P-treated patients, the pH fluctuated between 1.8 and 3.5 and over 90% of the readings were less than pH 4. As compared to P, both C and R significantly suppressed H+ after breakfast, overnight, and over the 24-hr period. The mean pH after lunch was significantly higher in R than in P, but not in C. Over the 24-hr period, a higher percentage of the readings were above pH 4.0 in R as compared to C. During the night, 50% of the pH readings were above pH 4.0 in C and R, whereas in P 50% of the pH readings were less than pH 2.0. The integrated gastrin responses after each meal were similar in C and R and were greater than in P. The biphasic response of the ratio of H+ and gastrin (H+/G) following each meal was suppressed by both H2-receptor antagonists, with numerically lower values obtained in R than in C. This study suggests that ranitidine 150 mg bid is superior to cimetidine 300 mg qid in suppressing the 24-hr intragastric acidity.

Adult↗

PubMed1985

Antisecretory and serum gastrin lowering effect of enprostil in patients with duodenal ulcer disease.

This study was designed to compare the effects of enprostil, a synthetic dehydro-prostaglandin E2, on 24-h intragastric pH and serum gastrin profile in patients with duodenal ulcer disease. The dosing regimen included 3 enprostil groups: 35 microgram h.s. (at bedtime), 70 micrograms h.s., and 35 micrograms b.i.d., compared with cimetidine 600 mg b.i.d., and with placebo. Ten patients with inactive duodenal ulcer disease were randomly assigned to all five treatment regimens for 1 wk each according to a Latin Square design. There was a 1-wk washout period between each treatment. Intragastric pH and serum gastrin measurements were carried out on the last day of each treatment week. In placebo-treated patients, intragastric pH rose after each meal and fluctuated between 1.5 and 3.5. Enprostil 35 micrograms b.i.d. and cimetidine elevated pH after breakfast and during the night (p less than 0.05). The single nighttime dose of enprostil had a marked effect on pH only when given in the dose of 70 micrograms and this effect lasted over 13.5 h. The pH values during the night were similar in the groups treated with enprostil 35 micrograms b.i.d. and 70 micrograms h.s. During the daytime, the readings at or above pH 4 were placebo, 5%; cimetidine, 21%; enprostil 35 micrograms b.i.d., 34%. During the nighttime, the readings greater than or equal to 4 were placebo, 12%; cimetidine, 29%; enprostil 35 micrograms b.i.d., 39%; 35 micrograms h.s., 19%, and 70 micrograms h.s., 38%. The postprandial rise in serum gastrin was greatly enhanced by cimetidine, but the change after breakfast was dramatically blunted by enprostil 35 micrograms b.i.d. Gastrin concentration was increased with cimetidine during the night but there was no difference in gastrin concentration overnight between all regimens of enprostil and placebo. This study suggests that (a) enprostil 35 micrograms b.i.d. is as effective as cimetidine 600 mg b.i.d. in suppressing postprandial and nocturnal intragastric acidity; (b) enprostil 35 micrograms b.i.d. and 70 micrograms at night are similarly potent in suppressing nocturnal acidity; and (c) in addition to its cytoprotective effect, enprostil has potent antisecretory and antigastrin properties.

Adult↗